1a. Objectives (from AD-416):
The research objectives are to develop slow pyrolysis (or torrefaction) and activation processes to convert agricultural feedstock (crop residues, manures, processing wastes, and biorefinery by-products) into:
(1) chars that can be used as industrial adsorbents;
(2) chars that can be used as soil amendments which improve soil quality, water quality, and sequester carbon;
(3) chars that can be used as energy sources (in combustion or gasification); and
(4) bio-gas and bio-oil co-products that provide some of the heat and power requirements of the pyrolysis/torrefaction/activation operations and possibly excess heat/power for sale.

1b. Approach (from AD-416):
The approach will be to take agricultural feedstocks (crop residues, animal manure, and biorefinery waste) and heat them under different gas atmospheres to a set temperature. In order to create chars for target applications, the temperature, heating time, and gas atmosphere will be varied, as well as performing pretreatment (before heating) or post treatment of the chars to obtain desired properties. The products will be tested for target applications in our laboratories and also with collaborators with expertise in ammonia adsorption, soil amendments, bio-oil production, and large-scale pyrolysis.

3. Progress Report:
The reported progress addresses Objectives 1 and 2 of the research project and focuses on the goal of National Program 213 and 306 action plans.
Long-term effectiveness of biochar for heavy metal stabilization depends upon biochar’s sorptive property and stability in soil. To understand the role of different chemical groups that exist on the surface of the biochar and how they affect heavy metal stabilization, biochars were made from cottonseed hull and flax shive. In another study, phosphorous-rich biochar from chicken manure was produced at two different temperatures (350 and 650° Celsius) and these chars were added to contaminated soils. It was found that biochar created at the lower of the two temperatures could stabilize the metals better. Two manuscripts were published about the results.
Sorption and degradation are the primary processes controlling the efficiency and runoff contamination risk of pesticides. In one study, we investigated how the soil type (clayey, acidic Puerto Rican forest soil and heavy metal contaminated small arms range soils of sandy and peaty nature) impacted the sorption of several pesticides (which names are triazine, malathion, parathion, and diazinon) to the soil. The degree of sorption on different soils showed the following increasing trend: triazine

4. Accomplishments
1. Heavy metals were stabilized in contaminated soils. Industrial and military sites are of considerable environmental risk when the soil contains toxic heavy metals. In collaboration with Army Research Laboratory and U.S. Department of Defense partners, ARS scientists at the Southern Regional Research Center in New Orleans, LA, demonstrated specific bindings of lead, copper, and zinc by carboxyl surface functional groups of biochar. Based on that, we developed biochar activation protocols for increasing the amount of oxygen-containing groups for selective metal binding. We also demonstrated that phosphorous and other elemental characteristics of manure biochars can be used to predict heavy metals stabilization in contaminated soils. This is positive news as there are an estimated 12,000 military and non-military shooting ranges where lead is the major risk driver and legislative concern.

2. Activated chars made from almond shells were used to clean up water. Aquifer drinking water in San Joaquin Valley, CA, is contaminated with a compound called dibromochloropropane from pest treatments. The water is filtered with large activated carbon filters before introduced into city drinking water systems. ARS researchers at the Southern Regional Research Center in New Orleans, LA, charred almond shells and then activated them with steam. These activated chars were then tested for their capability of removing the contaminants from water. Laboratory experiments were so successful that the researchers built a small column and installed it at a well site in CA and operated it for several months at 100% removal efficiency. A large number of these wells exist in the San Joaquin Valley and it would be beneficial if sustainable resources such as local almond shells could be used as replacement products for activated carbons from coal.